A synopsis:Research published in 1999 [1] illustrated how the environmental release of GE microorganisms might cause widespread ecological damage.

When a GE strain of Klebsiella planticola bacteria was added to microcosms with sandy soil and wheat plants, the numbers of bacterial and fungal feeding nematodes increased significantly, and the plants died. When the parental, non-GE strain was added, only bacterial feeding nematodes increased, but the plants did not die. The introduction of either strain to soil without plants did not alter the nematode community.

K. planticola is a common lactose-fermenting soil bacterium. The GE bacteria were engineered to produce increased ethanol concentrations in fermentors that convert agricultural wastes to ethanol. Fermentation residues, including the GE bacteria, were proposed for use as a soil amendment.

The study provided evidence that the GE bacteria could persist under conditions found in some soil ecosystems, and for long enough to stimulate changes in soil biota that could affect plant growth and nutrient cycling processes. While it is unclear to what extent these observations occur in situ, the finding that the GE bacteria cause plant death raised the possibility that this soil amendment could kill crops in the fields if it was used.